What I mean to say is: a good deck is only a percentage of the battle. Any 1300e deck that's built with the current meta in mind will be able to hit 1400e if you're lucky/persistent enough to secure that win streak.

Yup. You need to be winning a definitely large majority of your matches, as the rewards for winning are so low, and those for failure so high, particularly earlier in the week. I haven't been able to crack it yet.

like you are playing gheist or roots and are constantly running into stop: cards (example for bad luck) or something like that
or you get 2/2 splits while your opponent's often get 3/1 splits or way lower star counts. that kind of luck